Male, in truth, that is insincerely suave sort (8)
I believe the answer is:
smoothie
'insincerely suave sort' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps there's a link between them I don't understand?
'male in truth that is' is the wordplay.
'male' becomes 'm' (common abbreviation).
'in' is an insertion indicator.
'truth' becomes 'sooth' (synonyms).
'that is' becomes 'ie' (abbreviation for id est, 'that is' in Latin).
'm' placed into 'sooth' is 'smooth'.
'smooth'+'ie'='SMOOTHIE'
Can you help me to learn more?
(Other definitions for smoothie that I've seen before include "Sweet talker" , "Drink of pureed fresh fruit with yoghurt or milk" , "Dairy fruit drink" , "Thick fruity drink - charmer" , "Smarmy type" .)